This invention relates generally to handling fasteners such as screws and the like for their use in automated fastening operations. More specifically this invention concerns feeding of fasteners such as screws in sequential groups and particularly to feeding groups of fasteners in a sequence to an applicator for applying a workpiece with each group of fasteners to a base or substrate at each of a series of sites.
Various implements are utilized for automatically applying fasteners to a workpiece and they often require the delivery of fasteners to an applicator implement or implements at a single worksite to carry out the fastening operation at that worksite. One such application is described in U.S. Pat. No. 3,221,967 to MacKenzie et al. in which groups of nails are serially fed to a nailing die that holds them against the outsole of a shoe at an attaching station at which the nails are driven through the heel and into the heel portion of an outsole. This application requires only one fastening location. However, in some applications it is desirable to deliver groups of fasteners to each of a multiple number of fastening locations at the same time.
One such application is found in equipment for automatically applying fasteners between doors and door jambs. In this application a multiple number of screws must be driven into the door and adjacent jamb through the openings in each hinge leaf, usually three or more for each leaf.
In such hinging equipment screws are first collated from a collection in an overhead screw box and a group individual screws are then fed simultaneously from the box, each through a separate tube to one of the hinge openings for driving therethrough by a driving implement into the door or jamb. In order to apply hinges at multiple locations along the side of the door, stationary hinging equipment is provided for each location or a single hinger is mounted on a carriage for movement between each hinging site to apply all of the hinges consecutively.
In the carriage-mounted hinger the screw box is mounted on the carriage above the driving implement at the hinge openings and moves between hinging sites with the rest of the hinging equipment on the carriage. The screw box necessarily contributes a substantial amount of mass and weight to carriage and thus may limit the speed and accuracy of performance of the hinger functions. Thus, it would be desirable have a rapid screw supply to the hinging equipment on the carriage without requiring the screw box to be on the carriage.
Another approach for delivering a series of fasteners simultaneously to a workplace is seen in U.S. Pat. No. 5,480,087. In this approach, a vibrating feed hopper collates screws and delivers them in a column down a delivery chute to an outlet confronting a slide assembly extending normal to the chute that is mounted for movement between a ready position to one side of the chute and a dump position to the other side. The slide assembly contains a series of compartments spaced along its length each for receiving and holding a screw from the delivery chute. When the slide assembly moves from the dump position to the ready position it moves past the end of the delivery chute and each compartment of the slide assembly receives a screw from the chute. When the slide assembly returns to the dump position the screws are simultaneously released through the bottom of their compartments each into its own delivery tube, for delivery to a separate screwdriver at a workplace.
The foregoing delivery system is essentially equivalent in result to the screw hopper arrangement described for the hinger application in that a mass of random screws are organized and simultaneously discharged in groups, each through a separate delivery tube, to a workplace. Adapted for the carriage-mounted hinger operation earlier described, this system, including its feed hopper, must be mounted on the carriage, with the attendant weight and mass shortcomings mentioned for the screw box delivery system. Moreover, in this system the screws must be inserted into the slide assembly one by one, with attendant delay. Also, the slide assembly is only capable of holding one charge of screws for the delivery tubes and must return to the ready position after each dump.